Vascular endothelium, interacting with circulating blood cells and humoral mediators, plays a central role in the pathogenesis of acute and chronic inflammation, hemostasis and thrombosis, immunological reactions, vascular injury and repair, and various vascular diseases. Since its inception, 25 years ago, this Program Project has combined cell and molecular biological, biochemical, morphological, molecular genetic, and experimental pathological approaches in animal models to gain new insights into the active role of the endothelium in these important disease processes. In this competitive renewal application, we propose to define intra/intercellular signaling pathways that integrate and regulate various endothelial-dependent mechanisms in inflammation, autoimmunity and response-to-injury reactions, using both in vitro and in vivo experimental strategies. Project 1 will study mechanisms and phenotypic consequences of signaling via endothelial E-selectin during leukocyte interactions in inflammation. Dr. Luscinskas' project will focus on the dynamic regulation of leukocyte trafficking via lateral junctional and non-junctional pathways in activated endothelium. Dr. Aird's project will characterize the genetic regulatory programs elicited by thrombin stimulation of protease-activated receptors in endothelium. Dr. Magadas' project will examine the role of the small Ras-like GTPases, Rap1 and Rap2, in the regulation of neutrophil-endothelial interactions. Cell Biology Core will provide well characterized vascular cell cultures (human, mouse, wild-type, mutant); monoclonal hybridoma maintenance; isolation of human blood cells; adenoviral transfection. Morphology Core will as assist in immnohistochemistry, in situ hybridization, and histopathologic examination of tissues. Physiological and Molecular Imaging Support Core will support intravital and confocal microscopy; computerized image analysis. Core D (Administrative) will provide administrative, secretarial and laboratory management support for the Program.